The present invention relates to cochlear implant prostheses and in particular to a method and apparatus for adjusting the operation of such a prosthesis in order to optimise the benefit of the therapy provided by the prosthesis to a user.
It is known that individual patients using a cochlear implant system differ in their ability to benefit from different speech coding strategies. These coding strategies may differ in the number of channels activated, the dynamic or fixed allocation of channels to electrodes and the rate of stimulation for each channel. For example, some patients show significant improvements in open-set speech understanding when converting from a relatively low rate of stimulation of 250 Hz per channel (for example as provided by the SPEAK stimulation strategy used in some of the products manufactured by the applicant) to rates of 1200 Hz per channel or more (for example as provided by the ACE stimulation strategy also used in some of the products manufactured by the applicant) while other stimulation parameters, such as the number of channels and their allocation to electrodes remain unchanged. Other patients show no improvement, or even a reduction in benefit, when the stimulation rate is increased from low rates to high rates.
Consequently at present the adjustment of operation of the implant in order to optimise the benefit of the therapy provided to a patient by a cochlear implant prosthesis is to some extent a hit-or-miss affair. In particular comments must be sought from the patient as to whether or not the benefit of the prosthesis is improved or decreased upon making an adjustment in operation. There are a number of problems associated with this prior art approach. For example the adjustment is not made according to any quantitative parameter but rather is based on the somewhat subjective judgements of the patient.
Furthermore some patients, for example young children, may not be able to readily indicate an improvement or decrease in the quality of their hearing perception during the adjustment process. Yet a further problem is that the present approach does not readily lend itself to automation, relying as it does on the conscious feedback of the patient.
It is an object of the present invention to provide a method for setting a cochlear implant prosthesis to an appropriate operation mode which overcomes the previously described problems.
According to a first aspect of the invention, there is provided a method for adjusting the operation of a cochlear implant prosthesis, said method including the steps of:
recording at least one neural response in respect of at least one electrode of said cochlear implant prosthesis;
b) determining a selected parameter from said recording;
c) determining an optimum operation mode for said cochlear implant prothesis selected on the basis of said selected parameter; and
d) adjusting the operation of said cochlear implant prosthesis to operatively cause said cochlear implant prosthesis to operative in said optimum operation mode.
According to a second aspect a method for adjusting the operation of a cochlear prosthesis including the steps of:
a) recording neural responses in relation to a plurality of electrodes of said cochlear implant prosthesis;
b) determining a corresponding plurality of selected parameters from said neural responses;
c) calculating a combined selected parameter from at least some of said plurality of selected parameters;
d) determining an optimum stimulation rate on the basis of said combined selected parameters; and
e) adjusting the operation of said cochlear implant prosthesis thereby causing said prosthesis to operatively apply stimulations to at least some of said plurality of electrodes, all of said plurality of electrodes, and/or any other available electrodes, at a rate dependent on said optimum stimulation rate.
According to third aspect a system for adjusting the operation of a cochlear prosthesis, said cochlear prosthesis including a means for evoking neural responses of the auditory system to applied stimulation, said system including:
a) processing means coupled to said cochlear prosthesis and arranged to analyse said neural responses in order to determine an optimal performance mode dependent on at least one selected parameter derived from said neural responses and to cause said cochlear prosthesis to operate in said optimal mode;